New Research Suggests Solar System May Have Once Harbored Super-Earths

Thanks to recent surveys of exoplanets—planets in solar systems other than our own—we know that most planetary systems typically have one or more super-Earths (planets that are substantially more massive than Earth but less massive than Neptune) orbiting closer to their suns than Mercury does. In March, researchers showed that our own solar system may have once had these super-Earths, but they were destroyed by Jupiter's inward and outward migration through the solar system. This migration would have gravitationally flung small planetesimals through the solar system, setting off chains of collisions that would push any interior planets into the sun.

In May, a new radio telescope array called the Owens Valley Long Wavelength Array (OV-LWA) saw its first light. Developed by a consortium led by Caltech, the OV-LWA has the ability to image simultaneously the entire sky at radio wavelengths with unmatched speed, helping astronomers to search for objects and phenomena that pulse, flicker, flare, or explode.

Plants are masters of photosynthesis—the process of turning carbon dioxide, sunlight, and water into oxygen and sugar. Inspired by this natural and energy-efficient process, Caltech researchers have created an "artificial leaf" that takes in CO2, sunlight, and water to produce hydrogen fuels. This solar-powered system, one researcher says, shatters all of the combined safety, performance, and stability records for artificial leaf technology by factors of 5 to 10 or more.

Credit: Santiago Lombeyda and Robin Betz

Potassium Salt Outperforms Precious Metals As a Catalyst

Rare precious metals have been the standard catalyst for the formation of carbon-silicon bonds, a process crucial to the synthesis of a host of products from new medicines to advanced materials. However, they are expensive, inefficient, and produce toxic waste byproducts. This February, Caltech researchers discovered a much more sustainable catalyst in the form of a simple potassium salt that is one of the most abundant metals on Earth and thousands of times less expensive than other commonly used catalysts. In addition, the potassium salt is much more effective at running challenging chemical reactions than state-of-the-art precious metal complexes.

The year 2015 proved to be another groundbreaking year for research at Caltech. From seeing quantum motion, to reconfiguring jellyfish limbs, to measuring stellar magnetic fields, researchers continued to ask and answer the deepest scientific questions.

In case you missed any of them, here are 15 stories highlighting a few of the discoveries, methods, and technologies that came to life at Caltech in 2015.